This invention relates to a coal-water fuel slurry and engine systems for utilizing the fuel slurry. In particular, the invention concerns systems with reciprocating internal-combustion engines such as slow-speed diesel engines and their operation with fuel slurries consisting of water and very fine particulate coal.
The rapidly increasing price of oil and uncertainty as to its availability has led to increased interest in the use of alternative fuels such as coal. One area of investigation has concerned fuels for internal-combustion engines such as diesel engines wherein coal is substituted for all or a portion of the liquid petroleum fuel conventionally employed. For example, fuel mixtures of pulverized coal and air have been proposed for diesel engines. Tests of such coal-air mixtures in modern diesel engines have generally been unsuccessful, however, due to incomplete combustion and difficulties in introducing the fuel into the engines. Coal-oil slurries have also been investigated as diesel engine fuels. However, in order to maintain fluid viscosities suitable for injecting the coal-oil slurry into the engine, the coal content is limited to a maximum of about 30-40 percent by weight. Thus, while a reduction in oil consumption could be achieved through use of coal-oil slurries, a large fraction of this fuel remains oil.
Accordingly, it is an object of the invention to provide a coal-water fuel slurry suitable for a reciprocating internal-combustion engine.
It is an object of the invention to provide a method for operating an internal-combustion engine fueled by a coal-water slurry so that the water acts as a carrier for the coal and also contributes to the work output of the engine.
It is also an object of the invention to provide a diesel engine system for combustion of a coal-water fuel slurry.
It is a further object of the invention to provide a method for operating a slow-speed diesel engine using a fuel slurry of micronized coal and water.